In recent years, a digital still camera and a digital video camera (hereinafter, referred merely to as digital camera) capable of converting an optical image of an object into an electrical image signal to be outputted therefrom have rapidly come into widespread use.
The digital cameras are roughly classified into two groups: namely, one is a full auto model aiming at an improvement in speed of auto focus, a reduction in size and weight of a main body, or the like; and the other is a high-end model provided with a focus ring for performing a manual operation of focusing and an aperture ring for performing a manual operation of exposure setting. Recently, since quality of images taken by the digital camera has been improved, popularity of the high-end model which can provide users with satisfaction to operate by themselves has also been increased.
The digital camera includes an imaging device provided with an image sensor, such as a CCD (Charge Coupled Device) or the like. The imaging device has a lens barrel for holding an imaging optical system. The lens barrel for use in a digital camera which can be manually operated is usually provided with operating members, such as cylindrical zoom ring, focus ring, aperture ring, and the like. There is disclosed in, for example, Patent Document 1, a camera provided with a lens barrel provided with a zoom ring, a focus ring, and an aperture ring, which can be manually operated. The camera described in Patent Document 1 can perform zooming by operating the zoom ring, focusing by operating the focus ring, and changes in aperture by operating the aperture ring, separately.
The camera described in Patent Document 1 has an AF/MF changeover switch, in addition to the focus ring, for selectively switching between an auto focus mode of automatically performing focusing and a manual focus mode of performing focusing by manual operation. According to the camera described in Patent Document 1, when the manual focus mode is selected, a focus motor is driven based on the amount of rotation and a rotational direction of the focus ring, so that the focus lens is moved in an optical axis direction.
Additionally, the camera described in Patent Document 1 has an exposure setting dial, in addition to the aperture ring, for switching exposure modes. According to the lens barrel described in Patent Document 1, it is possible to select, by operating the exposure setting dial, a desired mode out of a program AE mode in which the exposure is fully automatically set, an aperture priority AE mode in which the exposure is set based on an aperture being set, a shutter speed priority AE mode in which the exposure is set based on a shutter speed being set, and a manual exposure mode in which the exposure is fully manually set.
According to the camera described in Patent Document 1, when the aperture priority AE mode or the manual exposure mode is selected, an aperture motor is driven based on the amount of rotation and the rotational direction of the aperture ring to thereby operate an aperture blade, so that the exposure is controlled.
Meanwhile, there is disclosed, in Patent Document 2, a lens device provided with a front spherical lens, a first moving lens unit, an iris device, a second moving lens unit, a zoom ring for moving the first moving lens unit to an optical axis, an iris ring for changing an iris aperture of the iris device, a focus ring for moving the second moving lens unit to the optical axis.
According to the lens device described in Patent Document 2, the first moving lens unit and the zoom ring, the iris device and the iris ring, and the second moving lens unit and the focus ring constitute integrated blocks, respectively. For that reason, it is configured such that respective blocks are stacked in order and fixed with screws or the like in assembling the lens device.    [Patent Document 1] Japanese Unexamined Patent Publication (Kokai) No. 2003-29131    [Patent Document 2] Japanese Unexamined Patent Publication (Kokai) No. 2002-207154